Data accessing a network may be input into a large amount of value-added service devices, such as an anti-virus device, an accelerating device, a firewall device and a Network Address Translation (NAT) device. Traffic has to pass through these service devices without distinction, so unnecessary burdens may be brought to these devices, and the optimization of service resources may be restricted. In addition, the configuration may be complex, which makes it very difficult to realize a quick change of service configurations.
Aiming at the above problems, a Service Function Chain (SFC) mode is proposed. In the SFC mode, all serving services are integrated, and a service overlay layer is virtualized, so as to form a service topology. The service overlay layer is decoupled from the underlying network, so as not to be limited by the structure of the underlying network. The framework is shown in FIG. 1. The service through which the traffic passes may be determined by the SFC. The SFC may allocate different SFCs (which is implemented by an entry classifying device) to traffics at different levels by adding a Service Function Path Identifier (SFPID) to each SFC and classifying messages. A forwarding device may forward the message according the identifier of the SFC. As such, different service chain processing may be implemented for different traffics, so as to implement differentiated demands.
At present, the processing of the SFC is shown in FIG. 1. Different Service Functions (SF) or Service Function Forwarders (SFF) may be selected, according to the SFPID carried in the message, to forward a message. That is, for a message received from a classifier or an SFF, the SFF may forward the message to an SF belonging to this service chain path according to the SFPID of the message. For a message received from an SF, the SFF may select a next hop according to the SFPID of the message, and then send the message to a next SFF according to an address of the next hop.
For a Wide Area Network (WAN), some service functions therein may lease the service functions of other networks to perform complex processing. For example, some service functions in a Data Center (DC) network may be leased to perform some special processing on the traffic. In such a case, the traffic needs to enter the DC network. However, the specific service functions and connection relations in the DC network may be shielded to the lessee, and the devices in the DC network cannot identify the SFCID of the WAN. In this scenario, SFC supporting for end-to-end traffic cannot be implemented.
Aiming at the problem that SFC supporting for cross-network end-to-end traffic cannot be implemented, an effective solution has not been proposed.